Frequently Asked Questions

Plastic pumps and magnetic drive pumps for aggressive and hazardous fluids – developed and manufactured in Germany. On this page, we address the most frequently asked questions regarding materials, sealing concepts, operation, and applications. Can't find the right answer? Send us a non-binding pump enquiry – we will respond within 24 hours.

Pump selection & materials

I want to pump a corrosive or aggressive liquid – does SCHMITT have the right pump?

Yes. SCHMITT specialises in the pumping of aggressive, corrosive and hazardous fluids. For most pumping applications, we have a suitable plastic or magnetic drive pump in our range. Just provide us with the fluid, concentration, temperature, flow rate, and head. We will gladly recommend the appropriate series and suitable material.

Are there SCHMITT plastic pumps available in different materials?

Yes. Most SCHMITT plastic pumps are available in polypropylene (PP) and polyvinylidene fluoride (PVDF). For particularly demanding media, we also offer high-performance fluoropolymers as well as metallic versions:

• PP – economical standard material for many acids, alkalis, and salt solutions.
• PVDF – higher chemical and thermal resistance, e.g., for stronger acids.
• ETFE (NEOCHEM Base) and PFA (NEOCHEM Core) – for the most aggressive media and higher temperatures.
• Stainless steel 1.4571 and Hastelloy C4 – for specific series and special applications.

Which material is right for my media?

The critical factors are media, concentration, and operating temperature. The compatibility of our materials with nearly all chemicals can be found in our chemical resistance list. As a general rule, higher concentration and higher temperature require a more resistant material. If in doubt, we will check your specific case – send us a pump enquiry.

What is the difference between PP and PVDF?

PP (polypropylene) is the economical standard and is well suited for many acids, alkalis, and salt solutions at moderate temperatures. PVDF (polyvinylidene fluoride) is chemically and thermally more resilient and is chosen when media, concentration, or temperature exceed the limits of PP. The economically sensible choice of material depends on the specific case – we always recommend a resistant, yet not oversized material.

What does NEOCHEM Base and NEOCHEM Core refer to?

NEOCHEM is our series of high-performance fluoropolymers for particularly aggressive fluids. NEOCHEM Base is made of ETFE and can be used at temperatures up to about 95 °C; NEOCHEM Core is made of PFA for operating temperatures up to approximately 150 °C. These materials are used where PP and PVDF reach their limits.

Which pump is suitable for hydrofluoric acid (HF)?

Hydrofluoric acid imposes high demands on material and sealing. A magnetically coupled version in PVDF with silicon carbide bearings and FEP seals has proven effective. Since HF is highly toxic, we generally recommend a hermetically sealed design. Provide us with your operating data – we will determine the suitable combination for you.

Which pump is suitable for sulphuric acid, hydrochloric acid, or sodium hydroxide?

This strongly depends on concentration and temperature. Rough guideline: diluted media can often be pumped in PP, while higher concentrations require PVDF or a fluoropolymer. Metals such as stainless steel are usually not resistant to hydrochloric and sulphuric acid. For higher acid concentrations, we also recommend a magnetically coupled, hermetically sealed pump. The final pump selection will be based on your specific specifications.

Sealing & Magnetic drive

I need to securely prevent leaks of the smallest quantities – are there hermetically sealed SCHMITT pumps?

Yes. For environmentally or health-hazardous liquids, we offer hermetically sealed and TA-Luft approved magnetic drive pumps without dynamic shaft sealing. These include the MPN, SMP, and P series as well as our highly efficient NEOLUTION NHM.

Magnetic drive or mechanical seal – which concept is better?

Both concepts have their merits:

• Mechanical seal – economical and proven for non-critical media or in the presence of ferromagnetic particles in the fluid.
• Magnetic drive – hermetically sealed, without wearing shaft seals; the first choice for toxic, environmentally hazardous, or crystallizing media.

As a general rule: The more critical the fluid, the more likely the use of a magnetic drive. We are happy to advise you on which concept is the most economical for your application.

How does a magnetic drive pump work?

The motor drives an external magnetic ring. This transmits its torque contactlessly through a containment pot to an internal magnetic ring, which is connected to the impeller. The containment pot completely seals the pumping chamber from the outside – the pump is thus hermetically sealed and operates without wearing shaft seals.

What should I consider when using a magnetic drive pump?

Two points are important:

• Maintain minimum flow rate – a portion of the fluid lubricates and cools the sliding bearings; therefore, the pump should not run against a closed valve for extended periods.
• No ferromagnetic solids – magnetic particles could accumulate in the area of the magnetic drive. For fluids containing solids, we will advise you on the appropriate solution.

Operation & Installation

Does a centrifugal pump need to be vented before operation?

Yes. Before commissioning, the pump must be completely filled and vented. Running dry without fluid can damage the sliding bearings and seals.

What is the difference between “non-self-priming” and “self-priming”?

Non-self-priming centrifugal pumps cannot vent an empty suction line on their own – they must operate with a flooded suction or be filled before starting. Self-priming pumps vent the suction line without additional auxiliary devices and can also draw fluid from lower tanks. SCHMITT centrifugal pumps are generally non-self-priming; therefore, the suction line must always remain filled (e.g., via a check valve).

Can a SCHMITT centrifugal pump run dry?

This depends on the series:

• Series T (vertical submersible pumps) – dry-run capable, as there is no shaft seal in the fluid.
• Certain designs of Series MPN – also dry-run capable.
• NEOLUTION NHM – thanks to the patented sliding bearing design, temporarily dry-run tolerant (up to approx. 15 minutes) and additionally capable of hot running in case of malfunction, e.g., with the pressure or suction side closed, for up to 8 hours.

If permanent dry running is to be expected, we recommend a dry-run capable series or a dry-run protection system. Please contact us.

Can I install a horizontal centrifugal pump vertically?

A vertical installation is possible as long as the pump remains fully filled and vented. However, for permanent use in tanks and pits, we offer specially designed vertical submersible pumps of Series T.

What does NPSH mean and why is it important?

NPSH describes the inlet pressure that a pump requires at its entrance to avoid cavitation. If the available inlet (NPSHa) is less than the pump's requirement (NPSHr), vapor bubbles will form, reducing performance and damaging components. This is especially important with hot, evaporating fluids or long suction lines. We check the NPSH reserve during the design phase.

How do I properly set up the pump?

The setup determines the suction conditions:

• Next to the container with bottom inlet – optimal conditions; the fluid flows to the pump.
• Next to the container with inlet over the edge – the suction height reduces the NPSH margin.
• Above the container (suction operation) – the most demanding; the suction line must always remain filled for non-self-priming pumps. Alternatively, self-priming pumps like our series SMP can be used.

Does SCHMITT also offer pumps for ATEX zones?

Yes. Depending on the pump type, we offer ATEX versions for zones 1 and 2 in various temperature classes (e.g., T3 or T4). The classification of your system is performed by you or your person responsible for explosion protection – let us know the requirements, and we will supply the appropriate version.

Industries & Applications

Which pumps does SCHMITT use in galvanics and surface technology?

Galvanics and surface technology are among our core industries. For electrolytes, pickling, degreasing, and rinse baths, we supply durable plastic pumps – for crystallisation-prone or particularly aggressive fluids, in hermetically sealed, magnetically coupled design with silicon carbide sliding bearings.

Are SCHMITT pumps suitable for the semiconductor and electronics industry?

Yes. For wet chemistry in semiconductor manufacturing, high-purity, highly corrosion-resistant materials are required. Our plastic series made of PVDF and PP are used here. Renowned companies in the industry trust SCHMITT.

Do you offer pumps for air scrubbers and gas scrubbers?

Yes. In exhaust gas scrubbers, aggressive washing liquids circulate in a closed loop. Our corrosion-resistant plastic and magnetic drive pumps are designed for continuous operation in such circulation systems and have been in use for decades at the leading manufacturers of such systems.

Are SCHMITT pumps suitable for the chemical industry and laboratories?

Yes. From the process plant to the pilot plant, our pumps convey acids, alkalis, solvents, and other demanding fluids. Through the choice of materials (PP, PVDF, ETFE, PFA) and the sealing concept, we precisely adapt the pump to your fluid.

Economics & Sustainability

How energy-efficient are SCHMITT pumps?

Very efficient: The NEOLUTION NHM series achieves efficiencies of up to 76%. With NEOLUTION technology, up to 50% electricity costs can be saved compared to conventional solutions – a significant contribution to operating costs and CO₂ balance for continuously operating pumps.

How durable are SCHMITT pumps?

SCHMITT pumps are designed for longevity: many systems continue to operate reliably even after more than 25 years. We manufacture in Germany using high-quality materials and check each pump 100% before it leaves our facility. The MPN and NHM series can also be serviced on-site in just a few minutes and without special tools.

Service, Delivery & Purchase

I need a 3D model of the pump for my system planning.

Sure. We provide 3D models of all pumps in common formats (e.g., STEP). Please contact us at sales@schmitt-pumpen.de or call: 07243 / 5453-0.

Where can I buy SCHMITT pumps?

In Germany, you can buy SCHMITT pumps directly from the manufacturer. Outside of Germany, we will connect you with our qualified distribution partners in many countries.

What is the delivery time?

We usually manufacture and deliver standard pumps within a week.

Are SCHMITT centrifugal pumps subject to export restrictions?

Some series are subject to export restrictions. If you have questions regarding export, we are happy to assist you.

My pump is not working as desired – what support can I get?

In every operating manual, you will find a troubleshooting table with causes and remedies. If you cannot resolve the issue, we will personally assist you with advice and support – by phone or email.

Can I get spare parts and operating manuals for my pump?

Yes. We supply spare parts and provide the appropriate operating manual for all current series. Please let us know the series and size of your pump, and we will assist you quickly.

Does SCHMITT also have pumps for private applications (garden pond, basement drainage)?

In principle, SCHMITT pumps can also be used privately – however, they are designed for the transport of aggressive liquids in industrial and commercial applications. For ponds or basements, there are usually more economical standard solutions.

I would like to send a pump for repair – what should I consider?

Please ensure that you empty and flush the pump thoroughly before shipping and indicate the fluid that was pumped, so that we can take the necessary safety measures. You can provide this information on the decontamination declaration, which you should send to us in advance at sales@schmitt-pumpen.de or include in the package.

How do I submit a pump enquiry?

The fastest way is through the enquiry form on our website – or via email at sales@schmitt-pumpen.de or by phone at 07243 / 5453-0. It is helpful to provide information about the fluid, concentration, temperature, flow rate, and head. We will respond within 24 hours with a suitable proposal.